This invention relates to a duplexing and switching system and method in a multiplexed system consisting of multiprocessors, wherein the multiplexed system is kept in continuous normal operation by duplexing of functions and by high speed switching to a non-failure side when the multiplexed system is out of order.
In general, optical cable television systems, mobile communication systems and video on demand systems operate duplexly in "A" and "B" directions. In addition, in such systems, high speed switching to a non-failure side is performed when troubles occur.
Typically, for such functions, the "A" and "B" sides check their counterpart's state when switching to the non-failure side. That is, "A" side checks "B" side's state continuously and "B" side checks "A" side's state continuously for discriminating whether troubles occur and switching to a counterpart when troubles occur. For A and B sides to check their counterpart's state, information on the counterpart is stored in a register or memory at predetermined regions. A processor accesses the information at the regions by polling and process the failure state.
The conventional art uses very expensive complicated hardware such as processors and peripheral circuits. In addition, such hardware can not be controlled by units or groups, thus making it difficult to apply to multisystems.